Fix fmt_spaces indenting in the context of 3 or more newlines

compiler/fmt/src/spaces.rs

@@ -46,7 +46,7 @@ where
         match space {
             Newline => {
                 if !encountered_comment && (consecutive_newlines < 2) {
-                    if iter.peek() == Some(&&Newline) {
+                    if iter.peek() == Some(&&Newline) && consecutive_newlines < 1 {
                         buf.push('\n');
                     } else {
                         newline(buf, indent);

compiler/fmt/tests/test_fmt.rs

@@ -2110,6 +2110,31 @@ mod test_fmt {
         ));
     }
 
+    #[test]
+    fn inner_def_with_triple_newline_before() {
+        expr_formats_to(
+            indoc!(
+                r#"
+                \x ->
+
+
+                    m1 = insert m n powerOf10
+
+                    42
+                "#
+            ),
+            indoc!(
+                r#"
+                \x ->
+
+                    m1 = insert m n powerOf10
+
+                    42
+                "#
+            ),
+        );
+    }
+
     #[test]
     fn when_guard() {
         expr_formats_same(indoc!(