Fix ICE due to carriage return w/ multibyte char

Based off of
972560b83f

src/test/ui/issues/issue-70381.rs

@@ -0,0 +1,6 @@
+// Test that multi-byte unicode characters with missing parameters do not ICE.
+
+fn main() {
+  println!("\r¡{}")
+  //~^ ERROR 1 positional argument in format string
+}

src/test/ui/issues/issue-70381.stderr

@@ -0,0 +1,8 @@
+error: 1 positional argument in format string, but no arguments were given
+  --> $DIR/issue-70381.rs:4:16
+   |
+LL |   println!("\r¡{}")
+   |                ^^
+
+error: aborting due to previous error
+