App.__get_project_refs(): Fix recursion stop conditions

App.__get_project_refs() recurses into the package dependency graph, but
the recursion end conditions only work well if all required packages are
present. Whether a required package is installed or not is decided upon a
wrong condition, however - existence of the project's project directory,
which may or may not be misleading for both the -devel and the -run
requirements. This can lead to various unwanted outcomes: Missing packages
happily inserted into the recursion buffer, process termination instead of
recursion stop, path lookup errors instead of a clearer "unmet dependency"
message (No project path found for module xyz, Failed to find directory of
project foo).

This commit cleanly detects if -run or -devel are installed and makes the
walk stop or raise under the appropriate conditions:

1. -run missing but required, raises unmet dependency
2. -devel missing but required, raises unmet dependency
3. -run present, no -devel required, stop recursing

Signed-off-by: Jan Lindemann <jan@janware.com>
Assisted-by: unsloth/Qwen3.8-27B-GGUF:Q4_K_M with pi.dev v0.85.1

src/python/jw/pkg/App.py

@@ -206,6 +206,7 @@ class App(Base):
         names_only: bool,
     ) -> None:
         name = self.strip_module_from_spec(spec)
+        mod = re.split('([=><]+)', spec)[0].strip()
         if names_only:
             spec = name
         if spec in buf:
@@ -215,6 +216,15 @@ class App(Base):
                 buf.append(spec)
             return
         visited.add(spec)
+        needed_subpackage = 'devel' if mod.endswith(('-dev', '-devel')) else 'run'
+        if not self.is_installed(name, devel = True):
+            if not mod.endswith(('-dev', '-devel')):
+                if self.is_installed(name, devel = False):
+                    return
+            raise Exception(
+                f'Unmet dependency on {mod}: the -{needed_subpackage} package '
+                f'of project {name} is not installed'
+            )
         vals = self.get_value(name, section, key)
         log(
             DEBUG,