# Buggy code
def kernel_config():
    """Create a config object with IPython kernel options"""
    from IPython.config.loader import Config, load_pyconfig_files
    from IPython.core.application import get_ipython_dir
    from spyderlib.config import CONF
    from spyderlib.utils.programs import is_module_installed

    # ---- IPython config ----
    try:
        profile_path = osp.join(get_ipython_dir(), "profile_default")
        ip_cfg = load_pyconfig_files(
            ["ipython_config.py", "ipython_qtconsole_config.py"], profile_path
        )
    except:
        ip_cfg = Config()

    # ---- Spyder config ----
    spy_cfg = Config()

    # Until we implement Issue 1052
    spy_cfg.InteractiveShell.xmode = "Plain"

    # Run lines of code at startup
    run_lines_o = CONF.get("ipython_console", "startup/run_lines")
    if run_lines_o:
        spy_cfg.IPKernelApp.exec_lines = [x.strip() for x in run_lines_o.split(",")]
    else:
        spy_cfg.IPKernelApp.exec_lines = []

    # Pylab configuration
    mpl_installed = is_module_installed("matplotlib")
    pylab_o = CONF.get("ipython_console", "pylab")

    if mpl_installed and pylab_o:
        # Get matplotlib backend
        backend_o = CONF.get("ipython_console", "pylab/backend", 0)
        backends = {
            0: "inline",
            1: "auto",
            2: "qt",
            3: "osx",
            4: "gtk",
            5: "wx",
            6: "tk",
        }
        mpl_backend = backends[backend_o]

        # Automatically load Pylab and Numpy, or only set Matplotlib
        # backend
        autoload_pylab_o = CONF.get("ipython_console", "pylab/autoload")
        if autoload_pylab_o:
            spy_cfg.IPKernelApp.exec_lines.append("%pylab {0}".format(mpl_backend))
        else:
            spy_cfg.IPKernelApp.exec_lines.append("%matplotlib {0}".format(mpl_backend))

        # Inline backend configuration
        if backends[backend_o] == "inline":
            # Figure format
            format_o = CONF.get("ipython_console", "pylab/inline/figure_format", 0)
            formats = {0: "png", 1: "svg"}
            spy_cfg.InlineBackend.figure_format = formats[format_o]

            # Resolution
            spy_cfg.InlineBackend.rc = {
                "figure.figsize": (6.0, 4.0),
                "savefig.dpi": 72,
                "font.size": 10,
                "figure.subplot.bottom": 0.125,
                "figure.facecolor": "white",
                "figure.edgecolor": "white",
            }
            resolution_o = CONF.get("ipython_console", "pylab/inline/resolution")
            spy_cfg.InlineBackend.rc["savefig.dpi"] = resolution_o

            # Figure size
            width_o = float(CONF.get("ipython_console", "pylab/inline/width"))
            height_o = float(CONF.get("ipython_console", "pylab/inline/height"))
            spy_cfg.InlineBackend.rc["figure.figsize"] = (width_o, height_o)

    # Run a file at startup
    use_file_o = CONF.get("ipython_console", "startup/use_run_file")
    run_file_o = CONF.get("ipython_console", "startup/run_file")
    if use_file_o and run_file_o:
        spy_cfg.IPKernelApp.file_to_run = run_file_o

    # Autocall
    autocall_o = CONF.get("ipython_console", "autocall")
    spy_cfg.ZMQInteractiveShell.autocall = autocall_o

    # To handle the banner by ourselves in IPython 3+
    spy_cfg.ZMQInteractiveShell.banner1 = ""

    # Greedy completer
    greedy_o = CONF.get("ipython_console", "greedy_completer")
    spy_cfg.IPCompleter.greedy = greedy_o

    # Sympy loading
    sympy_o = CONF.get("ipython_console", "symbolic_math")
    if sympy_o:
        lines = sympy_config(mpl_backend)
        spy_cfg.IPKernelApp.exec_lines.append(lines)

    # Merge IPython and Spyder configs. Spyder prefs will have prevalence
    # over IPython ones
    ip_cfg._merge(spy_cfg)
    return ip_cfg


# Traceback (UnboundLocalError)
An error ocurred while starting the kernel
Traceback (most recent call last):
File "C:\Users\Dani\Anaconda3\lib\site‑packages\spyderlib\widgets\externalshell\start_ipython_kernel.py", line 169, in
ipk_temp.config = kernel_config()
File "C:\Users\Dani\Anaconda3\lib\site‑packages\spyderlib\widgets\externalshell\start_ipython_kernel.py", line 119, in kernel_config
lines = sympy_config(mpl_backend)
UnboundLocalError: local variable 'mpl_backend' referenced before assignment

# Fixed code
def kernel_config():
    """Create a config object with IPython kernel options"""
    from IPython.config.loader import Config, load_pyconfig_files
    from IPython.core.application import get_ipython_dir
    from spyderlib.config import CONF
    from spyderlib.utils.programs import is_module_installed

    # ---- IPython config ----
    try:
        profile_path = osp.join(get_ipython_dir(), "profile_default")
        ip_cfg = load_pyconfig_files(
            ["ipython_config.py", "ipython_qtconsole_config.py"], profile_path
        )
    except:
        ip_cfg = Config()

    # ---- Spyder config ----
    spy_cfg = Config()

    # Until we implement Issue 1052
    spy_cfg.InteractiveShell.xmode = "Plain"

    # Run lines of code at startup
    run_lines_o = CONF.get("ipython_console", "startup/run_lines")
    if run_lines_o:
        spy_cfg.IPKernelApp.exec_lines = [x.strip() for x in run_lines_o.split(",")]
    else:
        spy_cfg.IPKernelApp.exec_lines = []

    # Pylab configuration
    mpl_backend = None
    mpl_installed = is_module_installed("matplotlib")
    pylab_o = CONF.get("ipython_console", "pylab")

    if mpl_installed and pylab_o:
        # Get matplotlib backend
        backend_o = CONF.get("ipython_console", "pylab/backend", 0)
        backends = {
            0: "inline",
            1: "auto",
            2: "qt",
            3: "osx",
            4: "gtk",
            5: "wx",
            6: "tk",
        }
        mpl_backend = backends[backend_o]

        # Automatically load Pylab and Numpy, or only set Matplotlib
        # backend
        autoload_pylab_o = CONF.get("ipython_console", "pylab/autoload")
        if autoload_pylab_o:
            spy_cfg.IPKernelApp.exec_lines.append("%pylab {0}".format(mpl_backend))
        else:
            spy_cfg.IPKernelApp.exec_lines.append("%matplotlib {0}".format(mpl_backend))

        # Inline backend configuration
        if backends[backend_o] == "inline":
            # Figure format
            format_o = CONF.get("ipython_console", "pylab/inline/figure_format", 0)
            formats = {0: "png", 1: "svg"}
            spy_cfg.InlineBackend.figure_format = formats[format_o]

            # Resolution
            spy_cfg.InlineBackend.rc = {
                "figure.figsize": (6.0, 4.0),
                "savefig.dpi": 72,
                "font.size": 10,
                "figure.subplot.bottom": 0.125,
                "figure.facecolor": "white",
                "figure.edgecolor": "white",
            }
            resolution_o = CONF.get("ipython_console", "pylab/inline/resolution")
            spy_cfg.InlineBackend.rc["savefig.dpi"] = resolution_o

            # Figure size
            width_o = float(CONF.get("ipython_console", "pylab/inline/width"))
            height_o = float(CONF.get("ipython_console", "pylab/inline/height"))
            spy_cfg.InlineBackend.rc["figure.figsize"] = (width_o, height_o)

    # Run a file at startup
    use_file_o = CONF.get("ipython_console", "startup/use_run_file")
    run_file_o = CONF.get("ipython_console", "startup/run_file")
    if use_file_o and run_file_o:
        spy_cfg.IPKernelApp.file_to_run = run_file_o

    # Autocall
    autocall_o = CONF.get("ipython_console", "autocall")
    spy_cfg.ZMQInteractiveShell.autocall = autocall_o

    # To handle the banner by ourselves in IPython 3+
    spy_cfg.ZMQInteractiveShell.banner1 = ""

    # Greedy completer
    greedy_o = CONF.get("ipython_console", "greedy_completer")
    spy_cfg.IPCompleter.greedy = greedy_o

    # Sympy loading
    sympy_o = CONF.get("ipython_console", "symbolic_math")
    if sympy_o:
        lines = sympy_config(mpl_backend)
        spy_cfg.IPKernelApp.exec_lines.append(lines)

    # Merge IPython and Spyder configs. Spyder prefs will have prevalence
    # over IPython ones
    ip_cfg._merge(spy_cfg)
    return ip_cfg