bpp-lsp: ProgramPool: Verify parsing was successful before changing pool state

This prevents crashes which may come from storing 'nullptr' parse results in the program pool's state, and later (unthinkingly) using them as if they were valid pointers.
It also prevents us from losing diagnostic information about programs which have been parsed, which have also undergone incomplete updates that can't yet be fully re-parsed

Author: rail5

src/lsp/ProgramPool.cpp

@@ -202,6 +202,12 @@ std::shared_ptr<bpp::bpp_program> ProgramPool::re_parse_program(const std::strin
 	if (has_program(file_path)) {
 		size_t index = program_indices[file_path];
 		std::string main_source_file = programs[index]->get_main_source_file();
+
+		auto new_program = _parse_program(main_source_file);
+		if (new_program == nullptr) {
+			return nullptr; // Return nullptr if parsing fails
+		}
+
 		programs[index] = _parse_program(main_source_file);
 		open_files[file_path] = true; // Mark the file as open
 
@@ -221,6 +227,13 @@ std::shared_ptr<bpp::bpp_program> ProgramPool::re_parse_program(
 	if (has_program(file_path)) {
 		size_t index = program_indices[file_path];
 		std::string main_source_file = programs[index]->get_main_source_file();
+
+		auto new_program = _parse_program(main_source_file, replacement_file_contents);
+
+		if (new_program == nullptr) {
+			return nullptr; // Return nullptr if parsing fails
+		}
+
 		programs[index] = _parse_program(main_source_file, replacement_file_contents);
 		open_files[file_path] = true; // Mark the file as open