SCM - fix treeview comparison function (microsoft#203325)

Author: lszomoru

src/vs/workbench/contrib/scm/browser/scmViewPane.ts

@@ -1171,28 +1171,16 @@ export class SCMTreeSorter implements ITreeSorter<TreeElement> {
 			return 1;
 		}
 
-		if (isSCMViewSeparator(one)) {
-			if (!isSCMHistoryItemGroupTreeElement(other) && !isSCMResourceGroup(other)) {
-				throw new Error('Invalid comparison');
-			}
-
-			return 0;
-		}
-
 		if (isSCMResourceGroup(one)) {
-			if (!isSCMResourceGroup(other)) {
-				throw new Error('Invalid comparison');
-			}
+			return isSCMResourceGroup(other) ? 0 : -1;
+		}
 
-			return 0;
+		if (isSCMViewSeparator(one)) {
+			return isSCMResourceGroup(other) ? 1 : -1;
 		}
 
 		if (isSCMHistoryItemGroupTreeElement(one)) {
-			if (!isSCMHistoryItemGroupTreeElement(other) && !isSCMResourceGroup(other) && !isSCMViewSeparator(other)) {
-				throw new Error('Invalid comparison');
-			}
-
-			return 0;
+			return isSCMHistoryItemGroupTreeElement(other) ? 0 : 1;
 		}
 
 		if (isSCMHistoryItemTreeElement(one)) {