File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/offsetbox.py", line 81, in _get_packed_offsets
    sep = (total - sum(w_list)) / (len(w_list) - 1.)
TypeError: unsupported operand type(s) for -: 'NoneType' and 'float'

Module bismark raised an exception: Traceback (most recent call last):
  File "/Users/philewels/GitHub/MultiQC/scripts/multiqc", line 427, in multiqc
    output = mod()
  File "/Users/philewels/GitHub/MultiQC/multiqc/modules/bismark/bismark.py", line 167, in __init__
    self.bismark_mbias_plot()
  File "/Users/philewels/GitHub/MultiQC/multiqc/modules/bismark/bismark.py", line 496, in bismark_mbias_plot
    plot = linegraph.plot(datasets, pconfig)
  File "/Users/philewels/GitHub/MultiQC/multiqc/plots/linegraph.py", line 139, in plot
    return matplotlib_linegraph(plotdata, pconfig)
  File "/Users/philewels/GitHub/MultiQC/multiqc/plots/linegraph.py", line 402, in matplotlib_linegraph
    plt.tight_layout(rect=[0,0.08,1,0.92])
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/pyplot.py", line 1366, in tight_layout
    fig.tight_layout(pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/figure.py", line 2273, in tight_layout
    pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/tight_layout.py", line 328, in get_tight_layout_figure
    pad=pad, h_pad=h_pad, w_pad=w_pad)
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/tight_layout.py", line 115, in auto_adjust_subplotpars
    if ax.get_visible()])
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/axes/_base.py", line 4179, in get_tightbbox
    bb.append(child._legend_box.get_window_extent(renderer))
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/offsetbox.py", line 262, in get_window_extent
    w, h, xd, yd, offsets = self.get_extent_offsets(renderer)
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/offsetbox.py", line 384, in get_extent_offsets
    for c in self.get_visible_children()]
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/offsetbox.py", line 255, in get_extent
    w, h, xd, yd, offsets = self.get_extent_offsets(renderer)
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/offsetbox.py", line 474, in get_extent_offsets
    sep, self.mode)
  File "/Users/philewels/miniconda2/envs/work/lib/python2.7/site-packages/matplotlib/offsetbox.py", line 81, in _get_packed_offsets
    sep = (total - sum(w_list)) / (len(w_list) - 1.)
TypeError: unsupported operand type(s) for -: 'NoneType' and 'float'