Philippe 19/08/2022: bugfix: deallocate ballon namelist data only if allocated

src/MNH/ini_balloon.f90

@@ -344,7 +344,7 @@ DO JI = 1, NBALLOONS
   END SELECT
 END DO
 
-CALL BALLOONS_NML_DEALLOCATE()
+IF ( NBALLOONS > 0 ) CALL BALLOONS_NML_DEALLOCATE()
 
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