fix(show): handle missing lockfile (#5242)

src/poetry/console/commands/show.py

@@ -129,6 +129,13 @@ lists all packages available."""
         if self.option("default"):
             only_groups.append("default")
 
+        if not self.poetry.locker.is_locked():
+            self.line_error(
+                "<error>Error: poetry.lock not found. Run `poetry lock` to create"
+                " it.</error>"
+            )
+            return 1
+
         locked_repo = self.poetry.locker.locked_repository(True)
 
         if only_groups:

tests/console/commands/test_show.py

@@ -1587,3 +1587,13 @@ required by
 """.splitlines()
     actual = [line.rstrip() for line in tester.io.fetch_output().splitlines()]
     assert actual == expected
+
+
+def test_show_errors_without_lock_file(tester: "CommandTester", poetry: "Poetry"):
+    assert not poetry.locker.lock.exists()
+
+    tester.execute()
+
+    expected = "Error: poetry.lock not found. Run `poetry lock` to create it.\n"
+    assert tester.io.fetch_error() == expected
+    assert tester.status_code == 1