Fix: Post-Simulation GUI Crashes & Results Parsing

[shubham148-st]

This PR resolves a series of intertwined bugs causing KeyError, ValueError, and Segmentation Faults when interacting with the GUI after a simulation fails, or when rendering results for MaterialStream components.

Changes

1. Missing Variable Definitions

• Added missing Fm_p[2] (Liquid Mass Flow) and Fm_p[3] (Vapour Mass Flow) keys to the MaterialStream variables dictionary in utils/Streams.py. This was absent and was causing MaterialStream: 'Fm_p[2]'` error and associated Segmentation Faults when clicking on output streams.

2. Equation Initialization Data Corruption

• Deprecated keywords xm_pc (mass fraction) and Fm_pc (mass flow) were being used in get_start_values() where json.dumps(x_pcarr) of utils/Streams.py, it now correctly uses xm_pcarr and Fm_pcarr.
• Fixed a silent KeyError bug in get_start_values() in utils/Streams.py. The method previously tried to access MW_p[2] and Cp_p[2] directly, which do not exist in the variables dict. This caused the method to abort early and skip setting valid starting guesses for H_p, S_p, and F_p. Replaced direct access with a safe .get() fallback.

3. Defensive Simulation Value Parsing

• Added a safety check in ext_data() in Flowsheet.py to skip parsing if result_data has fewer than 2 rows.
• In utils/Container.py: moved the update_tooltip_selectedVar() call into the if simulation_successful: block. Tooltips will no longer try to update using stale or failed string values if a simulation fails.

4. Safe Rendering

• In Streams.py replaced bare float(val) conversions in param_getter and param_getter_tooltip_selectedVar with a _safe_float() helper function. This prevents ValueError crashes if bad data accidentally enters the variable dictionary.
• In DockWidgetMaterialStream.py refactored the inline str(round(float(resultval), 4)) UI item rendering logic into a cleaner _safe_result() local helper function. It safely validates that the string is actually numeric using an advanced .isdigit() check before parsing, protecting the Results Tree/Table from crashing.