Added some more error handling (#1652)

Started adding error handling around every single RPC call from the
client to the agent. In this PR I've put some basic error handling in
place for `accept()`, `cancel()`, and `undo()` in `FixupController`.
There is also a bit of corner-case error handling added to
`EditCommandPrompt'.

## Test plan

Locally tested by inserting exceptions into the code paths. Will make
tests for this when we have integration tests, post-GA.

src/main/kotlin/com/sourcegraph/cody/edit/EditCommandPrompt.kt

@@ -548,29 +548,33 @@ class EditCommandPrompt(
   @RequiresEdt
   fun performOKAction() {
     val text = instructionsField.text
-    if (text.isNotBlank()) {
-      promptHistory.add(text)
-      val project = editor.project
-      // TODO: How do we show user feedback when an error like this happens?
-      if (project == null) {
-        logger.warn("Project was null when trying to add an edit session")
-        return
+    if (text.isBlank()) {
+      clearActivePrompt()
+      return
+    }
+    val activeSession = controller.getActiveSession()
+    promptHistory.add(text)
+    if (editor.project == null) {
+      val msg = "Null project for new edit session"
+      controller.getActiveSession()?.showErrorGroup(msg)
+      logger.warn(msg)
+      return
+    }
+
+    activeSession?.let { session ->
+      session.afterSessionFinished {
+        startEditCodeSession(text, if (session.isInserted) "insert" else "edit")
       }
+      session.undo()
+    } ?: run { startEditCodeSession(text) }
 
-      val activeSession = controller.getActiveSession()
-      activeSession?.let {
-        it.afterSessionFinished {
-          runInEdt {
-            EditCodeSession(
-                controller, editor, text, llmDropdown.item, if (it.isInserted) "insert" else "edit")
-          }
-        }
-        it.undo()
-      } ?: run { runInEdt { EditCodeSession(controller, editor, text, llmDropdown.item) } }
-    }
     clearActivePrompt()
   }
 
+  private fun startEditCodeSession(text: String, mode: String = "edit") {
+    runInEdt { EditCodeSession(controller, editor, text, llmDropdown.item, mode) }
+  }
+
   private fun makeCornerShape(width: Int, height: Int): RoundRectangle2D {
     return RoundRectangle2D.Double(
         0.0, 0.0, width.toDouble(), height.toDouble(), CORNER_RADIUS, CORNER_RADIUS)

src/main/kotlin/com/sourcegraph/cody/edit/sessions/FixupSession.kt

@@ -245,33 +245,49 @@ abstract class FixupSession(
     documentListener.setAcceptLensGroupShown(true)
   }
 
-  private fun showErrorGroup(hoverText: String) {
+  fun showErrorGroup(hoverText: String) {
     showLensGroup(LensGroupFactory(this).createErrorGroup(hoverText))
   }
 
   /** Subclass sends a fixup command to the agent, and returns the initial task. */
   abstract fun makeEditingRequest(agent: CodyAgent): CompletableFuture<EditTask>
 
   fun accept() {
-    CodyAgentService.withAgent(project) { agent ->
-      agent.server.acceptEditTask(TaskIdParam(taskId!!))
+    try {
+      CodyAgentService.withAgent(project) { agent ->
+        agent.server.acceptEditTask(TaskIdParam(taskId!!))
+      }
+    } catch (x: Exception) {
+      // Don't show error lens here; it's sort of pointless.
+      logger.warn("Error sending editTask/accept for taskId: ${x.localizedMessage}")
+      dispose()
     }
   }
 
   fun cancel() {
     if (taskId == null) {
       dispose()
     } else {
-      CodyAgentService.withAgent(project) { agent ->
-        agent.server.cancelEditTask(TaskIdParam(taskId!!))
+      try {
+        CodyAgentService.withAgent(project) { agent ->
+          agent.server.cancelEditTask(TaskIdParam(taskId!!))
+        }
+      } catch (x: Exception) {
+        // Error lens here is counterproductive as well.
+        logger.warn("Error sending editTask/accept for taskId: ${x.localizedMessage}")
+        dispose()
       }
     }
   }
 
   fun undo() {
     runInEdt { showWorkingGroup() }
-    CodyAgentService.withAgent(project) { agent ->
-      agent.server.undoEditTask(TaskIdParam(taskId!!))
+    try {
+      CodyAgentService.withAgent(project) { agent ->
+        agent.server.undoEditTask(TaskIdParam(taskId!!))
+      }
+    } catch (x: Exception) {
+      showErrorGroup("Error sending editTask/undo for taskId: ${x.localizedMessage}")
     }
   }