Remove errors that only occur in dev mode

[nolanlawson]

#3244 revealed a lot of cases where our functionality differs between dev mode and prod mode. Sometimes this makes sense (e.g. calling console.warn only in dev mode), but in other cases it can introduce surprising behavior, when you test in dev mode and then get a different result in prod mode.

We should audit each of these cases and (probably) defer to doing the same thing in dev mode as prod mode. (In practice, prod mode is reality – many people never test in dev mode.)

Cases to check (in Karma test code):

• if (process.env.NODE_ENV === ...)
• expect(...).toThrowErrorDev()
• expect(...).toThrowConnectedErrorDev()

[git2gus]

This issue has been linked to a new work item: W-12257612

[nolanlawson]

This is a really sneaky one that I haven't gotten around to fixing yet:

lwc/packages/@lwc/engine-core/src/framework/decorators/api.ts

Lines 87 to 93 in d004e93

	get(this: LightningElement): any {
	if (process.env.NODE_ENV !== 'production') {
	// Assert that the this value is an actual Component with an associated VM.
	getAssociatedVM(this);
	}
	return get.call(this);
	},

[nolanlawson]

Might have to save this one ^ for when we have API versioning. Turns out it throws an error in dev mode, but not prod mode, and only when the accessor is accessed internally: 893d693

Feels like it should just consistently throw in both prod and dev mode when the this is wrong.

[nolanlawson]

A big problem is this function. It throws an error in dev mode, but not in prod mode:

lwc/packages/@lwc/engine-core/src/framework/vm.ts

Lines 480 to 488 in f689896

	export function getAssociatedVM(obj: VMAssociable): VM {
	const vm = ViewModelReflection.get(obj);
	if (process.env.NODE_ENV !== 'production') {
	assertIsVM(vm);
	}
	return vm!;
	}

This function is called in many places.

[nolanlawson]

Synthetic shadow has a few of these, like this one:

lwc/packages/@lwc/synthetic-shadow/src/faux-shadow/traverse.ts

Lines 136 to 149 in 3a7e1b4

	if (process.env.NODE_ENV !== 'production') {
	assert.invariant(
	owner instanceof HTMLElement,
	`isNodeOwnedBy() should be called with an element as the first argument instead of ${owner}`
	);
	assert.invariant(
	node instanceof Node,
	`isNodeOwnedBy() should be called with a node as the second argument instead of ${node}`
	);
	assert.invariant(
	compareDocumentPosition.call(node, owner) & DOCUMENT_POSITION_CONTAINS,
	`isNodeOwnedBy() should never be called with a node that is not a child node of ${owner}`
	);
	}

[nolanlawson]

This is largely fixed, I'm going to call this one done for now. If something else comes up, we can open another issue.