Improve and cleanup CDS extractor packageManager

Improves the efficiency and logging of package dependency installation
tasks in the "packageManager" package of the CDS extractor source code.

Responds to peer feedback on related PR #195.

Extends unit test coverage for the `src/packageManager` code.

Author: data-douser

extractors/cds/tools/cds-extractor.ts

@@ -108,8 +108,8 @@ try {
     }
   } else {
     cdsExtractorLog(
-      'warn',
-      'No CDS projects were detected. This may indicate an issue with project detection logic.',
+      'error',
+      'No CDS projects were detected. This is an unrecoverable error as there is nothing to scan.',
     );
     // Let's also try to find CDS files directly as a backup check
     try {
@@ -129,10 +129,23 @@ try {
           'info',
           `Sample CDS files: ${allCdsFiles.slice(0, 5).join(', ')}${allCdsFiles.length > 5 ? ', ...' : ''}`,
         );
+        cdsExtractorLog(
+          'error',
+          'CDS files were found but no projects were detected. This indicates a problem with project detection logic.',
+        );
+      } else {
+        cdsExtractorLog(
+          'info',
+          'No CDS files found in the source tree. This may be expected if the source does not contain CAP/CDS projects.',
+        );
       }
     } catch (globError) {
       cdsExtractorLog('warn', `Could not perform direct CDS file search: ${String(globError)}`);
     }
+
+    // Exit early since we have no CDS projects to process
+    logExtractorStop(false, 'Terminated: No CDS projects detected');
+    process.exit(1);
   }
 } catch (error) {
   cdsExtractorLog('error', `Failed to build enhanced dependency graph: ${String(error)}`);
@@ -145,6 +158,30 @@ startPerformanceTracking('Dependency Installation');
 const projectCacheDirMap = installDependencies(dependencyGraph, sourceRoot, codeqlExePath);
 endPerformanceTracking('Dependency Installation');
 
+// Check if dependency installation resulted in any usable project mappings
+if (projectCacheDirMap.size === 0) {
+  cdsExtractorLog(
+    'error',
+    'No project cache directory mappings were created. This indicates that dependency installation failed for all discovered projects.',
+  );
+
+  // This is a critical error if we have projects but no cache mappings
+  if (dependencyGraph.projects.size > 0) {
+    cdsExtractorLog(
+      'error',
+      `Found ${dependencyGraph.projects.size} CDS projects but failed to install dependencies for any of them. Cannot proceed with compilation.`,
+    );
+    logExtractorStop(false, 'Terminated: Dependency installation failed for all projects');
+    process.exit(1);
+  }
+
+  // If we have no projects and no cache mappings, this should have been caught earlier
+  cdsExtractorLog(
+    'warn',
+    'No projects and no cache mappings - this should have been detected earlier.',
+  );
+}
+
 const cdsFilePathsToProcess: string[] = [];
 
 // Use the enhanced dependency graph to collect all `.cds` files from each project.