Close owned import roots during panic unwinding

internal/engine/import_acquisition.go

@@ -61,6 +61,16 @@ func acquireImportedInput(request importAcquisitionRequest, policy *acquisitionP
 }
 
 func acquireImportedWithAccess(request importAcquisitionRequest, policy *acquisitionPolicy, loadState *acquisitionState, tier *tierAcquisitionState, access *filesystemAccess, resolved resolvedFilesystemContext) (*composedDocument, []SourceInfo, []Diagnostic) {
+	closed := false
+	closeAccess := func() error {
+		if closed {
+			return nil
+		}
+		closed = true
+		return access.close()
+	}
+	defer func() { _ = closeAccess() }()
+
 	main := request.main
 	destination := request.input.input.destination
 	limits := policy.importLimits
@@ -73,13 +83,13 @@ func acquireImportedWithAccess(request importAcquisitionRequest, policy *acquisi
 	}
 	visited := tier.visited
 	if !access.contains(basePath) || (mainPath != "" && !access.contains(mainPath)) {
-		_ = access.close()
+		_ = closeAccess()
 		return nil, sourceInfos(main.source), []Diagnostic{importDiagnostic(CodeImportOutsideRoot, "selected source and import base must stay inside the configuration root", nil)}
 	}
 	for _, directory := range []string{access.rootPath, basePath} {
 		info, err := access.stat(directory)
 		if err != nil || !info.IsDir() {
-			_ = access.close()
+			_ = closeAccess()
 			return nil, sourceInfos(main.source), []Diagnostic{importDiagnostic(CodeImportInvalid, "configuration root and import base must be directories", nil)}
 		}
 	}
@@ -95,7 +105,7 @@ func acquireImportedWithAccess(request importAcquisitionRequest, policy *acquisi
 		mainResource = access.syntheticIdentity()
 	}
 	if previous, repeated := visited[mainResource]; repeated {
-		_ = access.close()
+		_ = closeAccess()
 		return nil, sourceInfos(main.source), []Diagnostic{importRepeatedDiagnostic(Location{SourceID: main.source.ID}, previous, importRoute{})}
 	}
 	accounting.sources++
@@ -125,7 +135,7 @@ func acquireImportedWithAccess(request importAcquisitionRequest, policy *acquisi
 	}
 
 	if diagnostic := state.checkInitialLimits(); diagnostic != nil {
-		_ = access.close()
+		_ = closeAccess()
 		return nil, cloneSourceInfos(state.sources), []Diagnostic{*diagnostic}
 	}
 
@@ -181,7 +191,7 @@ func acquireImportedWithAccess(request importAcquisitionRequest, policy *acquisi
 		scheduleAcquisitionScopes(&state.scope, indexImportDependencies(state.importGraph))
 	}
 
-	closeErr := access.close()
+	closeErr := closeAccess()
 	if len(diagnostics) != 0 {
 		if mainIsItem {
 			diagnostics = prependCompositionDiagnosticPaths(diagnostics, destination.Index(0))