numfmt: prevent panic if float precision specifier > 65535 (#12600)

src/uu/numfmt/src/format.rs

@@ -628,7 +628,7 @@ fn transform_to(
             "{:.precision$}",
             round_with_precision(i2, round_method, precision),
         )),
-        None if is_precision_specified => {
+        None if is_precision_specified && precision <= u16::MAX.into() => {
             let i2 = round_with_precision(i2, round_method, 0);
             localize(format!("{i2:.precision$}"))
         }

tests/by-util/test_numfmt.rs

@@ -1627,3 +1627,11 @@ fn test_multibyte_suffix_issue11937() {
         .succeeds()
         .stdout_is("   692.00€\n");
 }
+
+#[test]
+fn test_float_precision_greater_than_16bits() {
+    new_ucmd!()
+        .args(&["--to=iec", "--format=%.65536f", "1"])
+        .succeeds()
+        .stdout_is("1\n");
+}