Make Path::SetExtension("") not include a dot

src/platform/platform.cpp

@@ -185,8 +185,10 @@ Path Path::WithExtension(std::string ext) const {
     if(dot != std::string::npos) {
         withExt.raw.erase(dot);
     }
+    if(!ext.empty()) {
         withExt.raw += ".";
         withExt.raw += ext;
+    }
     return withExt;
 }
 

test/core/path/test.cpp

@@ -83,6 +83,7 @@ TEST_CASE(extension) {
 }
 
 TEST_CASE(with_extension) {
+    CHECK_EQ_STR(Path::From("foo.bar").WithExtension("").raw, "foo");
     CHECK_EQ_STR(Path::From("foo.bar").WithExtension("baz").raw, "foo.baz");
     CHECK_EQ_STR(Path::From("foo").WithExtension("baz").raw, "foo.baz");
 }