refactor(tvix): Make Store::buildPaths return a Status

Make Store::buildPaths return a Status with [[nodiscard]] rather than
throwing exceptions to signal failure. This is the beginning of a long
road to refactor the entire store API to be status/statusor based
instead of using exceptions.

Change-Id: I2e32371c95a25b87ad129987c217d49c6d6e0c85
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1745
Tested-by: BuildkiteCI
Reviewed-by: kanepyork <rikingcoding@gmail.com>

third_party/nix/src/nix-build/nix-build.cc

@@ -19,6 +19,7 @@
 #include "libstore/globals.hh"
 #include "libstore/store-api.hh"
 #include "libutil/affinity.hh"
+#include "libutil/status.hh"
 #include "libutil/util.hh"
 #include "nix/legacy.hh"
 
@@ -358,7 +359,7 @@ static void _main(int argc, char** argv) {
     }
 
     if (!dryRun) {
-      store->buildPaths(paths, buildMode);
+      util::OkOrThrow(store->buildPaths(paths, buildMode));
     }
   };