diff --git a/cmd/showbridge/main.go b/cmd/showbridge/main.go
index a7ff6e0..836df73 100644
--- a/cmd/showbridge/main.go
+++ b/cmd/showbridge/main.go
@@ -127,6 +127,9 @@ func readConfig(configPath string) (config.Config, error) {
 	}
 
 	validatedConfigBytes, err := json.Marshal(yamlMap)
+	if err != nil {
+		return config.Config{}, err
+	}
 
 	err = json.Unmarshal(validatedConfigBytes, &cfg)
 	if err != nil {
diff --git a/internal/api/api.go b/internal/api/api.go
index 144f9c7..4eac03b 100644
--- a/internal/api/api.go
+++ b/internal/api/api.go
@@ -58,7 +58,10 @@ func (as *ApiServer) Start(config config.ApiConfig) {
 	}
 
 	go func() {
-		as.server.ListenAndServe()
+		err := as.server.ListenAndServe()
+		if err != nil && err != http.ErrServerClosed {
+			as.logger.Error("server error", "error", err)
+		}
 		as.shutdown()
 	}()
 }
@@ -148,7 +151,7 @@ func (as *ApiServer) handleConfigHTTP(w http.ResponseWriter, req *http.Request)
 			http.Error(w, "Bad request", http.StatusBadRequest)
 			return
 		}
-		err, moduleErrors, routeErrors := as.configurableRouter.UpdateConfig(newConfig, true)
+		moduleErrors, routeErrors, err := as.configurableRouter.UpdateConfig(newConfig, true)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusConflict)
 			return
diff --git a/internal/processor/midi-control_change-create.go b/internal/processor/midi-control_change-create.go
index 1e9c76a..729347d 100644
--- a/internal/processor/midi-control_change-create.go
+++ b/internal/processor/midi-control_change-create.go
@@ -35,6 +35,11 @@ func (mccc *MIDIControlChangeCreate) Process(ctx context.Context, wrappedPayload
 
 	channelValue, err := strconv.ParseUint(channelBuffer.String(), 10, 8)
 
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	var controlBuffer bytes.Buffer
 	err = mccc.Control.Execute(&controlBuffer, templateData)
 
@@ -45,6 +50,11 @@ func (mccc *MIDIControlChangeCreate) Process(ctx context.Context, wrappedPayload
 
 	controlValue, err := strconv.ParseUint(controlBuffer.String(), 10, 8)
 
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	var valueBuffer bytes.Buffer
 	err = mccc.Value.Execute(&valueBuffer, templateData)
 
@@ -55,6 +65,11 @@ func (mccc *MIDIControlChangeCreate) Process(ctx context.Context, wrappedPayload
 
 	valueValue, err := strconv.ParseUint(valueBuffer.String(), 10, 8)
 
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	payloadMessage := midi.ControlChange(uint8(channelValue), uint8(controlValue), uint8(valueValue))
 	wrappedPayload.Payload = payloadMessage
 	return wrappedPayload, nil
diff --git a/internal/processor/midi-note_off-create.go b/internal/processor/midi-note_off-create.go
index 99369dd..6d7a8d3 100644
--- a/internal/processor/midi-note_off-create.go
+++ b/internal/processor/midi-note_off-create.go
@@ -35,6 +35,11 @@ func (mnoc *MIDINoteOffCreate) Process(ctx context.Context, wrappedPayload commo
 
 	channelValue, err := strconv.ParseUint(channelBuffer.String(), 10, 8)
 
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	var noteBuffer bytes.Buffer
 	err = mnoc.Note.Execute(&noteBuffer, templateData)
 
@@ -45,6 +50,11 @@ func (mnoc *MIDINoteOffCreate) Process(ctx context.Context, wrappedPayload commo
 
 	noteValue, err := strconv.ParseUint(noteBuffer.String(), 10, 8)
 
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	var velocityBuffer bytes.Buffer
 	err = mnoc.Velocity.Execute(&velocityBuffer, templateData)
 
@@ -54,6 +64,12 @@ func (mnoc *MIDINoteOffCreate) Process(ctx context.Context, wrappedPayload commo
 	}
 
 	velocityValue, err := strconv.ParseUint(velocityBuffer.String(), 10, 8)
+
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	payloadMessage := midi.NoteOffVelocity(uint8(channelValue), uint8(noteValue), uint8(velocityValue))
 	wrappedPayload.Payload = payloadMessage
 	return wrappedPayload, nil
diff --git a/internal/processor/midi-note_on-create.go b/internal/processor/midi-note_on-create.go
index fad5ef5..9b62a23 100644
--- a/internal/processor/midi-note_on-create.go
+++ b/internal/processor/midi-note_on-create.go
@@ -35,6 +35,11 @@ func (mnoc *MIDINoteOnCreate) Process(ctx context.Context, wrappedPayload common
 
 	channelValue, err := strconv.ParseUint(channelBuffer.String(), 10, 8)
 
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	var noteBuffer bytes.Buffer
 	err = mnoc.Note.Execute(&noteBuffer, templateData)
 
@@ -45,6 +50,11 @@ func (mnoc *MIDINoteOnCreate) Process(ctx context.Context, wrappedPayload common
 
 	noteValue, err := strconv.ParseUint(noteBuffer.String(), 10, 8)
 
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	var velocityBuffer bytes.Buffer
 	err = mnoc.Velocity.Execute(&velocityBuffer, templateData)
 
@@ -54,6 +64,11 @@ func (mnoc *MIDINoteOnCreate) Process(ctx context.Context, wrappedPayload common
 	}
 
 	velocityValue, err := strconv.ParseUint(velocityBuffer.String(), 10, 8)
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	payloadMessage := midi.NoteOn(uint8(channelValue), uint8(noteValue), uint8(velocityValue))
 	wrappedPayload.Payload = payloadMessage
 	return wrappedPayload, nil
diff --git a/internal/processor/midi-program_change-create.go b/internal/processor/midi-program_change-create.go
index 182941a..2e54c61 100644
--- a/internal/processor/midi-program_change-create.go
+++ b/internal/processor/midi-program_change-create.go
@@ -34,6 +34,11 @@ func (mpcc *MIDIProgramChangeCreate) Process(ctx context.Context, wrappedPayload
 
 	channelValue, err := strconv.ParseUint(channelBuffer.String(), 10, 8)
 
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	var programBuffer bytes.Buffer
 	err = mpcc.Program.Execute(&programBuffer, templateData)
 
@@ -44,6 +49,11 @@ func (mpcc *MIDIProgramChangeCreate) Process(ctx context.Context, wrappedPayload
 
 	programValue, err := strconv.ParseUint(programBuffer.String(), 10, 8)
 
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
+
 	payloadMessage := midi.ProgramChange(uint8(channelValue), uint8(programValue))
 	wrappedPayload.Payload = payloadMessage
 	return wrappedPayload, nil
diff --git a/internal/processor/script-js.go b/internal/processor/script-js.go
index 42557ee..719a97d 100644
--- a/internal/processor/script-js.go
+++ b/internal/processor/script-js.go
@@ -32,9 +32,13 @@ func (sj *ScriptJS) Process(ctx context.Context, wrappedPayload common.WrappedPa
 		}
 	}
 
-	sj.vm.SetProperty(sj.vm.GlobalObject(), sj.payloadAtom, wrappedPayload.Payload)
+	err := sj.vm.SetProperty(sj.vm.GlobalObject(), sj.payloadAtom, wrappedPayload.Payload)
+	if err != nil {
+		wrappedPayload.End = true
+		return wrappedPayload, err
+	}
 
-	_, err := sj.vm.Eval(sj.Program, quickjs.EvalGlobal)
+	_, err = sj.vm.Eval(sj.Program, quickjs.EvalGlobal)
 
 	if err != nil {
 		wrappedPayload.End = true
diff --git a/internal/processor/test/script-js_test.go b/internal/processor/test/script-js_test.go
index 8c5c202..17987ae 100644
--- a/internal/processor/test/script-js_test.go
+++ b/internal/processor/test/script-js_test.go
@@ -209,6 +209,13 @@ func TestBadScriptJS(t *testing.T) {
 				Params: test.params,
 			})
 
+			if err != nil {
+				if test.errorString != err.Error() {
+					t.Fatalf("script.js got error '%s', expected '%s'", err.Error(), test.errorString)
+				}
+				return
+			}
+
 			got, err := processorInstance.Process(t.Context(), common.WrappedPayload{Payload: test.payload})
 
 			if err == nil {