Additional graceful handling for pixi (microsoft#23942)

In addition to first PR
microsoft#23937

I've been able to repro aggressive errors of 
```
2024-08-12 13:59:21.087 [error] [Error: spawn pixi ENOENT
	at ChildProcess._handle.onexit (node:internal/child_process:286:19)
	at onErrorNT (node:internal/child_process:484:16)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  errno: -2,
  code: 'ENOENT',
  syscall: 'spawn pixi',
  path: 'pixi',
  spawnargs: [ '--version' ]
}
```

```
2024-08-12 13:59:20.794 [error] Reading directory to watch failed [Error: ENOENT: no such file or directory, scandir '/Users/anthonykim/Desktop/vscode-python/.pixi/envs'
	at Object.readdirSync (node:fs:1509:26)
	at t.readdirSync (node:electron/js2c/node_init:2:11418)
	at /Users/anthonykim/.vscode/extensions/ms-python.python-2024.13.2024080901-darwin-arm64/out/client/extension.js:2:583006
	at /Users/anthonykim/.vscode/extensions/ms-python.python-2024.13.2024080901-darwin-arm64/out/client/extension.js:2:583197
	at Array.map (<anonymous>)
	at d.initWatchers (/Users/anthonykim/.vscode/extensions/ms-python.python-2024.13.2024080901-darwin-arm64/out/client/extension.js:2:582915)
	at async d.ensureWatchersReady (/Users/anthonykim/.vscode/extensions/ms-python.python-2024.13.2024080901-darwin-arm64/out/client/extension.js:2:539326)] {
  errno: -2,
  code: 'ENOENT',
  syscall: 'scandir',
  path: '/Users/anthonykim/Desktop/vscode-python/.pixi/envs'
}
```

even when I dont have pixi in my workspace. Changing the log level on
this and adding more wraps around that should give necessary
hint/message when needed without crashing program.

---------

Co-authored-by: Karthik Nadig <kanadig@microsoft.com>

src/client/pythonEnvironments/base/locators/common/resourceBasedLocator.ts

@@ -4,7 +4,7 @@
 import { IDisposable } from '../../../../common/types';
 import { createDeferred, Deferred } from '../../../../common/utils/async';
 import { Disposables } from '../../../../common/utils/resourceLifecycle';
-import { traceError } from '../../../../logging';
+import { traceError, traceWarn } from '../../../../logging';
 import { arePathsSame, isVirtualWorkspace } from '../../../common/externalDependencies';
 import { getEnvPath } from '../../info/env';
 import { BasicEnvInfo, IPythonEnvsIterator, Locator, PythonLocatorQuery } from '../../locator';
@@ -36,7 +36,11 @@ export abstract class LazyResourceBasedLocator extends Locator<BasicEnvInfo> imp
     protected async activate(): Promise<void> {
         await this.ensureResourcesReady();
         // There is not need to wait for the watchers to get started.
-        this.ensureWatchersReady().ignoreErrors();
+        try {
+            this.ensureWatchersReady();
+        } catch (ex) {
+            traceWarn(`Failed to ensure watchers are ready for locator ${this.constructor.name}`, ex);
+        }
     }
 
     public async dispose(): Promise<void> {

src/client/pythonEnvironments/base/locators/lowLevel/fsWatchingLocator.ts

@@ -6,7 +6,7 @@ import * as path from 'path';
 import { Uri } from 'vscode';
 import { FileChangeType, watchLocationForPattern } from '../../../../common/platform/fileSystemWatcher';
 import { sleep } from '../../../../common/utils/async';
-import { traceError, traceVerbose } from '../../../../logging';
+import { traceVerbose, traceWarn } from '../../../../logging';
 import { getEnvironmentDirFromPath } from '../../../common/commonUtils';
 import {
     PythonEnvStructure,
@@ -32,13 +32,13 @@ function checkDirWatchable(dirname: string): DirUnwatchableReason {
         names = fs.readdirSync(dirname);
     } catch (err) {
         const exception = err as NodeJS.ErrnoException;
-        traceError('Reading directory to watch failed', exception);
+        traceVerbose('Reading directory failed', exception);
         if (exception.code === 'ENOENT') {
             // Treat a missing directory as unwatchable since it can lead to CPU load issues:
             // https://github.com/microsoft/vscode-python/issues/18459
             return 'directory does not exist';
         }
-        throw err; // re-throw
+        return undefined;
     }
     // The limit here is an educated guess.
     if (names.length > 200) {
@@ -117,7 +117,7 @@ export abstract class FSWatchingLocator extends LazyResourceBasedLocator {
             // that might be watched due to a glob are not checked.
             const unwatchable = await checkDirWatchable(root);
             if (unwatchable) {
-                traceError(`Dir "${root}" is not watchable (${unwatchable})`);
+                traceWarn(`Dir "${root}" is not watchable (${unwatchable})`);
                 return undefined;
             }
             return root;

src/client/pythonEnvironments/common/environmentManagers/pixi.ts

@@ -9,7 +9,7 @@ import { OSType, getOSType, getUserHomeDir } from '../../../common/utils/platfor
 import { exec, getPythonSetting, onDidChangePythonSetting, pathExists, pathExistsSync } from '../externalDependencies';
 import { cache } from '../../../common/utils/decorators';
 import { isTestExecution } from '../../../common/constants';
-import { traceError, traceVerbose, traceWarn } from '../../../logging';
+import { traceVerbose, traceWarn } from '../../../logging';
 import { OUTPUT_MARKER_SCRIPT } from '../../../common/process/internal/scripts';
 
 export const PIXITOOLPATH_SETTING_KEY = 'pixiToolPath';
@@ -119,7 +119,7 @@ export class Pixi {
                     yield customPixiToolPath;
                 }
             } catch (ex) {
-                traceError(`Failed to get pixi setting`, ex);
+                traceWarn(`Failed to get pixi setting`, ex);
             }
 
             // Check unqualified filename, in case it's on PATH.
@@ -182,7 +182,7 @@ export class Pixi {
             const pixiInfo: PixiInfo = JSON.parse(infoOutput.stdout);
             return pixiInfo;
         } catch (error) {
-            traceError(`Failed to get pixi info for ${cwd}`, error);
+            traceWarn(`Failed to get pixi info for ${cwd}`, error);
             return undefined;
         }
     }
@@ -199,15 +199,13 @@ export class Pixi {
             if (!versionOutput || !versionOutput.stdout) {
                 return undefined;
             }
-
             const versionParts = versionOutput.stdout.split(' ');
             if (versionParts.length < 2) {
                 return undefined;
             }
-
             return versionParts[1].trim();
         } catch (error) {
-            traceError(`Failed to get pixi version`, error);
+            traceVerbose(`Failed to get pixi version`, error);
             return undefined;
         }
     }