Improve error messages on reading invalid target files

... by including the details of the parse error.

2 files changed, 20 insertions, 6 deletions

diff --git a/src/buildtool/build_engine/base_maps/json_file_map.hpp b/src/buildtool/build_engine/base_maps/json_file_map.hpp
index 15aa6234..412631ca 100644
--- a/src/buildtool/build_engine/base_maps/json_file_map.hpp
+++ b/src/buildtool/build_engine/base_maps/json_file_map.hpp
@@ -84,11 +84,15 @@ auto CreateJsonFileMap(std::size_t jobs) -> JsonFileMap {
                       true);
             return;
         }
-        auto json = nlohmann::json::parse(*file_content, nullptr, false);
-        if (json.is_discarded()) {
-            (*logger)(fmt::format("JSON file {} does not contain valid JSON.",
-                                  json_file_path.string()),
-                      true);
+        auto json = nlohmann::json();
+        try {
+            json = nlohmann::json::parse(*file_content);
+        } catch (std::exception const& e) {
+            (*logger)(
+                fmt::format("JSON file {} does not contain valid JSON:\n{}",
+                            json_file_path.string(),
+                            e.what()),
+                true);
             return;
         }
         if (!json.is_object()) {
diff --git a/src/buildtool/main/main.cpp b/src/buildtool/main/main.cpp
index 35137d77..1c93d7c2 100644
--- a/src/buildtool/main/main.cpp
+++ b/src/buildtool/main/main.cpp
@@ -575,7 +575,17 @@ void SetupHashFunction() {
         Logger::Log(LogLevel::Error, "Cannot read file {}.", target_file);
         std::exit(kExitFailure);
     }
-    auto const json = nlohmann::json::parse(*file_content);
+    auto json = nlohmann::json();
+    try {
+        json = nlohmann::json::parse(*file_content);
+    } catch (std::exception const& e) {
+        Logger::Log(LogLevel::Error,
+                    "While searching for the default target in {}:\n"
+                    "Failed to parse json with error {}",
+                    target_file,
+                    e.what());
+        std::exit(kExitFailure);
+    }
     if (not json.is_object()) {
         Logger::Log(
             LogLevel::Error, "Invalid content in target file {}.", target_file);