remove gaurd against double explain

Author: baileympearson

src/utils.ts

@@ -260,12 +260,6 @@ export function decorateWithExplain(
   maxTimeMS?: number;
 } {
   type ExplainCommand = ReturnType<typeof decorateWithExplain>;
-  const isExplainCommand = (doc: Document): doc is ExplainCommand => 'explain' in command;
-
-  if (isExplainCommand(command)) {
-    return command;
-  }
-
   const { verbosity, maxTimeMS } = explain;
   const baseCommand: ExplainCommand = { explain: command, verbosity };
 

test/unit/utils.test.ts

@@ -1007,11 +1007,11 @@ describe('driver utils', function () {
   });
 
   describe('decorateWithExplain()', function () {
-    it('when the command is a valid explain command, the command is returned unmodified', function () {
-      const command = Object.freeze({ explain: { hello: 'world' } });
+    it('when the command is a valid explain command, the command is still wrapped', function () {
+      const command = { explain: { hello: 'world' } };
       const result = decorateWithExplain(command, Explain.fromOptions({ explain: true }));
 
-      expect(result).to.deep.equal(command);
+      expect(result).to.deep.equal({ explain: command, verbosity: 'allPlansExecution' });
     });
 
     it('when the options have a maxTimeMS, it is attached to the explain command', function () {