3 files changed, 29 insertions, 18 deletions

diff --git a/src/libexpr/value-to-json.cc b/src/libexpr/value-to-json.cc
index 4996a5bde..ac3986c87 100644
--- a/src/libexpr/value-to-json.cc
+++ b/src/libexpr/value-to-json.cc
@@ -43,6 +43,7 @@ json printValueAsJSON(EvalState & state, bool strict,
             break;
 
         case nNull:
+            // already initialized as null
             break;
 
         case nAttrs: {
@@ -59,7 +60,13 @@ json printValueAsJSON(EvalState & state, bool strict,
                     names.emplace(state.symbols[j.name]);
                 for (auto & j : names) {
                     Attr & a(*v.attrs->find(state.symbols.create(j)));
-                    out[j] = printValueAsJSON(state, strict, *a.value, a.pos, context, copyToStore);
+                    try {
+                        out[j] = printValueAsJSON(state, strict, *a.value, a.pos, context, copyToStore);
+                    } catch (Error & e) {
+                        e.addTrace(state.positions[a.pos],
+                            hintfmt("while evaluating attribute '%1%'", j));
+                        throw;
+                    }
                 }
             } else
                 return printValueAsJSON(state, strict, *i->value, i->pos, context, copyToStore);
@@ -68,8 +75,17 @@ json printValueAsJSON(EvalState & state, bool strict,
 
         case nList: {
             out = json::array();
-            for (auto elem : v.listItems())
-                out.push_back(printValueAsJSON(state, strict, *elem, pos, context, copyToStore));
+            int i = 0;
+            for (auto elem : v.listItems()) {
+                try {
+                    out.push_back(printValueAsJSON(state, strict, *elem, pos, context, copyToStore));
+                } catch (Error & e) {
+                    e.addTrace({},
+                        hintfmt("while evaluating list element at index %1%", i));
+                    throw;
+                }
+                i++;
+            }
             break;
         }
 
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index f8e0a0ca2..f78bd44ca 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1506,10 +1506,10 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
     printInfo("checking path existence...");
 
     StorePathSet validPaths;
-    PathSet done;
+    StorePathSet done;
 
     for (auto & i : queryAllValidPaths())
-        verifyPath(printStorePath(i), store, done, validPaths, repair, errors);
+        verifyPath(i, store, done, validPaths, repair, errors);
 
     /* Optionally, check the content hashes (slow). */
     if (checkContents) {
@@ -1595,19 +1595,12 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
 }
 
 
-void LocalStore::verifyPath(const Path & pathS, const StringSet & store,
-    PathSet & done, StorePathSet & validPaths, RepairFlag repair, bool & errors)
+void LocalStore::verifyPath(const StorePath & path, const StringSet & store,
+    StorePathSet & done, StorePathSet & validPaths, RepairFlag repair, bool & errors)
 {
     checkInterrupt();
 
-    if (!done.insert(pathS).second) return;
-
-    if (!isStorePath(pathS)) {
-        printError("path '%s' is not in the Nix store", pathS);
-        return;
-    }
-
-    auto path = parseStorePath(pathS);
+    if (!done.insert(path).second) return;
 
     if (!store.count(std::string(path.to_string()))) {
         /* Check any referrers first.  If we can invalidate them
@@ -1616,11 +1609,13 @@ void LocalStore::verifyPath(const Path & pathS, const StringSet & store,
         StorePathSet referrers; queryReferrers(path, referrers);
         for (auto & i : referrers)
             if (i != path) {
-                verifyPath(printStorePath(i), store, done, validPaths, repair, errors);
+                verifyPath(i, store, done, validPaths, repair, errors);
                 if (validPaths.count(i))
                     canInvalidate = false;
             }
 
+        auto pathS = printStorePath(path);
+
         if (canInvalidate) {
             printInfo("path '%s' disappeared, removing from database...", pathS);
             auto state(_state.lock());
diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 4125cacf4..c9b570eaa 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -314,8 +314,8 @@ private:
      */
     void invalidatePathChecked(const StorePath & path);
 
-    void verifyPath(const Path & path, const StringSet & store,
-        PathSet & done, StorePathSet & validPaths, RepairFlag repair, bool & errors);
+    void verifyPath(const StorePath & path, const StringSet & store,
+        StorePathSet & done, StorePathSet & validPaths, RepairFlag repair, bool & errors);
 
     std::shared_ptr<const ValidPathInfo> queryPathInfoInternal(State & state, const StorePath & path);