Fix some commands failing when an installed library has invalid version

Author: silvanocerza

arduino/libraries/librariesindex/index.go

@@ -136,12 +136,9 @@ func (idx *Index) FindLibraryUpdate(lib *libraries.Library) *Release {
 	if indexLib == nil {
 		return nil
 	}
-	// library.Version is nil when when the version field in
-	// a library descriptor is malformed and could not be parsed.
-	if lib.Version == nil {
-		return indexLib.Latest
-	}
-	if indexLib.Latest.Version.GreaterThan(lib.Version) {
+	// If a library.properties has an invalid version property, usually empty or malformed,
+	// the latest available version is returned
+	if lib.Version == nil || indexLib.Latest.Version.GreaterThan(lib.Version) {
 		return indexLib.Latest
 	}
 	return nil

arduino/libraries/librariesmanager/install.go

@@ -50,7 +50,7 @@ func (lm *LibrariesManager) InstallPrerequisiteCheck(indexLibrary *librariesinde
 			if installedLib.Location != libraries.User {
 				continue
 			}
-			if installedLib.Version.Equal(indexLibrary.Version) {
+			if installedLib.Version != nil && installedLib.Version.Equal(indexLibrary.Version) {
 				return installedLib.InstallDir, nil, ErrAlreadyInstalled
 			}
 			replaced = installedLib