Fixes #49173

src/vs/editor/common/model/textModel.ts

@@ -2505,10 +2505,10 @@ export class TextModel extends Disposable implements model.ITextModel {
 			const upLineNumber = lineNumber - distance;
 			const downLineNumber = lineNumber + distance;
 
-			if (upLineNumber < 1 || upLineNumber < minLineNumber) {
+			if (distance !== 0 && (upLineNumber < 1 || upLineNumber < minLineNumber)) {
 				goUp = false;
 			}
-			if (downLineNumber > lineCount || downLineNumber > maxLineNumber) {
+			if (distance !== 0 && (downLineNumber > lineCount || downLineNumber > maxLineNumber)) {
 				goDown = false;
 			}
 			if (distance > 50000) {

src/vs/editor/test/common/model/textModelWithTokens.test.ts

@@ -596,4 +596,25 @@ suite('TextModel.getLineIndentGuide', () => {
 			[0, 'include script'],
 		]);
 	});
+
+	test('issue #49173', () => {
+		let model = TextModel.createFromString([
+			'class A {',
+			'	public m1(): void {',
+			'	}',
+			'	public m2(): void {',
+			'	}',
+			'	public m3(): void {',
+			'	}',
+			'	public m4(): void {',
+			'	}',
+			'	public m5(): void {',
+			'	}',
+			'}',
+		].join('\n'));
+
+		const actual = model.getActiveIndentGuide(2, 4, 9);
+		assert.deepEqual(actual, { startLineNumber: 2, endLineNumber: 9, indent: 1 });
+		model.dispose();
+	});
 });