[terminal] IDEA-348915 Fix NPE when the new terminal survey dialog opened for test

There can be no info about most used shell only if the dialog is opened by the testing action. In the real scenario, the dialog just won't be shown if there are no executed commands because of the check in `BlockTerminalSurveyConfig.checkExtraConditionSatisfied`.
EA-1151653 fixed.

GitOrigin-RevId: f751b6dcaf46fa67bff26cbf4f3334312ed6b2f5

plugins/terminal/src/org/jetbrains/plugins/terminal/exp/TerminalUsageLocalStorage.kt

@@ -15,8 +15,9 @@ internal class TerminalUsageLocalStorage : PersistentStateComponent<TerminalUsag
   val executedCommandsNumber: Int
     get() = state.shellToExecutedCommandsNumber.values.sum()
 
-  val mostUsedShell: String
-    get() = state.shellToExecutedCommandsNumber.keys.maxBy { state.shellToExecutedCommandsNumber[it]!! }
+  /** Can be null only if [executedCommandsNumber] is zero */
+  val mostUsedShell: String?
+    get() = state.shellToExecutedCommandsNumber.keys.maxByOrNull { state.shellToExecutedCommandsNumber[it]!! }
 
   fun recordCommandExecuted(shellName: String) {
     state.shellToExecutedCommandsNumber.merge(shellName.lowercase(), 1, Int::plus)

plugins/terminal/src/org/jetbrains/plugins/terminal/exp/feedback/BlockTerminalFeedbackDialog.kt

@@ -1,6 +1,7 @@
 // Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package org.jetbrains.plugins.terminal.exp.feedback
 
+import com.intellij.openapi.diagnostic.thisLogger
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.util.NlsSafe
 import com.intellij.platform.feedback.dialog.BlockBasedFeedbackDialog
@@ -23,9 +24,18 @@ internal class BlockTerminalFeedbackDialog(project: Project, forTest: Boolean) :
 
   override val mySystemInfoData: BlockTerminalUsageData by lazy {
     val usageStorage = TerminalUsageLocalStorage.getInstance()
+    val rawMostUsedShell = usageStorage.mostUsedShell
+    val mostUsedShell = if (rawMostUsedShell == null && forTest) {
+      thisLogger().warn("No information about most used shell, because no commands were executed in the terminal")
+      "none"
+    }
+    else {
+      // It is guaranteed to be not null if it is not a test because of the check in BlockTerminalSurveyConfig.checkExtraConditionSatisfied
+      rawMostUsedShell!!
+    }
 
     BlockTerminalUsageData(
-      mostUsedShell = usageStorage.mostUsedShell,
+      mostUsedShell = mostUsedShell,
       executedCommandsNumber = usageStorage.executedCommandsNumber,
       feedbackMoment = getFeedbackMoment(project),
       systemInfo = CommonFeedbackSystemData.getCurrentData()