Improve direct serial connection error handling

Author: sioaeko

electron/osrSerial.ts

@@ -93,14 +93,14 @@ export class OsrSerialManager {
     }
     this.emitState()
 
-    const port = new SerialPortStream({
-      binding: getSerialPortBinding(),
-      path: targetPath,
-      baudRate,
-      autoOpen: false,
-    })
-
+    let port: RuntimeSerialPort
     try {
+      port = new SerialPortStream({
+        binding: getSerialPortBinding(),
+        path: targetPath,
+        baudRate,
+        autoOpen: false,
+      })
       await openPort(port)
     } catch (error) {
       this.state = {
@@ -207,12 +207,13 @@ export class OsrSerialManager {
 
     port.on('close', () => {
       if (port !== this.port) return
+      const wasActive = this.state.connectionState === 'connected' || this.state.connectionState === 'connecting'
       this.port = null
       this.state = {
         connectionState: 'disconnected',
         connectedPortPath: null,
         baudRate,
-        error: null,
+        error: wasActive ? 'Serial port closed unexpectedly.' : null,
       }
       this.emitState()
     })

src/services/osrSerial.ts

@@ -71,10 +71,25 @@ export class OsrSerialService {
     }
     this.onStateChange?.(this.state)
 
-    const nextState = await window.electronAPI.osrSerialConnect(portPath, baudRate)
-    this.state = nextState
-    this.onStateChange?.(nextState)
-    return nextState.connectionState === 'connected'
+    try {
+      const nextState = await window.electronAPI.osrSerialConnect(portPath, baudRate)
+      this.state = nextState
+      this.onStateChange?.(nextState)
+      return nextState.connectionState === 'connected'
+    } catch (error) {
+      const message = error instanceof Error && error.message
+        ? error.message
+        : 'Failed to open serial port.'
+      const nextState: OsrSerialState = {
+        connectionState: 'error',
+        connectedPortPath: null,
+        baudRate,
+        error: message,
+      }
+      this.state = nextState
+      this.onStateChange?.(nextState)
+      return false
+    }
   }
 
   async disconnect(): Promise<boolean> {