More tests.

test/printf-test.cc

@@ -265,6 +265,10 @@ TEST(PrintfTest, IgnorePrecisionForNonNumericArg) {
 
 TEST(PrintfTest, DynamicPrecision) {
   EXPECT_EQ("00042", str(fmt::sprintf("%.*d", 5, 42)));
+  EXPECT_THROW_MSG(fmt::sprintf("%.*d", 5.0, 42), FormatError,
+      "precision is not integer");
+  EXPECT_THROW_MSG(fmt::sprintf("%.*d"), FormatError,
+      "argument index is out of range in format");
   // TODO: more tests
 }