Add error message when Python is not installed

src/common/localize.ts

@@ -15,6 +15,7 @@ export namespace Common {
     export const ok = l10n.t('Ok');
     export const quickCreate = l10n.t('Quick Create');
     export const installPython = l10n.t('Install Python');
+    export const pythonNotFound = l10n.t('Python is not installed or not found in PATH. Please install Python to run Python files.');
 }
 
 export namespace WorkbenchStrings {

src/common/utils/executableExists.ts

@@ -0,0 +1,15 @@
+import which from 'which';
+
+/**
+ * Checks if an executable exists in the system PATH.
+ * @param executable The name or path of the executable to check.
+ * @returns A promise that resolves to true if the executable exists, false otherwise.
+ */
+export async function executableExists(executable: string): Promise<boolean> {
+    try {
+        await which(executable);
+        return true;
+    } catch (_err) {
+        return false;
+    }
+}

src/features/execution/runInBackground.ts

@@ -1,5 +1,8 @@
 import * as cp from 'child_process';
 import { PythonEnvironment, PythonBackgroundRunOptions, PythonProcess } from '../../api';
+import { showErrorMessage } from '../../common/window.apis';
+import { executableExists } from '../../common/utils/executableExists';
+import { Common } from '../../common/localize';
 
 export async function runInBackground(
     environment: PythonEnvironment,
@@ -10,6 +13,12 @@ export async function runInBackground(
     const args = environment.execInfo?.activatedRun?.args ?? environment.execInfo?.run.args ?? [];
     const allArgs = [...args, ...options.args];
 
+    // Check if the Python executable exists
+    if (!(await executableExists(executable))) {
+        await showErrorMessage(Common.pythonNotFound, { modal: true }, Common.installPython);
+        throw new Error(Common.pythonNotFound);
+    }
+
     const proc = cp.spawn(executable, allArgs, { stdio: 'pipe', cwd: options.cwd, env: options.env });
 
     return {

src/features/terminal/runInTerminal.ts

@@ -1,10 +1,12 @@
 import { Terminal, TerminalShellExecution } from 'vscode';
 import { PythonEnvironment, PythonTerminalExecutionOptions } from '../../api';
-import { onDidEndTerminalShellExecution } from '../../common/window.apis';
+import { onDidEndTerminalShellExecution, showErrorMessage } from '../../common/window.apis';
 import { createDeferred } from '../../common/utils/deferred';
 import { quoteArgs } from '../execution/execUtils';
 import { identifyTerminalShell } from '../common/shellDetector';
 import { ShellConstants } from '../common/shellConstants';
+import { executableExists } from '../../common/utils/executableExists';
+import { Common } from '../../common/localize';
 
 export async function runInTerminal(
     environment: PythonEnvironment,
@@ -20,6 +22,12 @@ export async function runInTerminal(
     const args = environment.execInfo?.activatedRun?.args ?? environment.execInfo?.run.args ?? [];
     const allArgs = [...args, ...(options.args ?? [])];
 
+    // Check if the Python executable exists
+    if (!(await executableExists(executable))) {
+        await showErrorMessage(Common.pythonNotFound, { modal: true }, Common.installPython);
+        return;
+    }
+
     if (terminal.shellIntegration) {
         let execution: TerminalShellExecution | undefined;
         const deferred = createDeferred<void>();