better checking for invalid plot options

[kcrisman]

Sage 6.5

sage: polar_plot(sec(x),(x,-pi/8,pi/8),ticks=[.1,None],aspect_ratio='auto')
/Users/.../sage-6.5/local/lib/python2.7/site-packages/IPython/core/formatters.py:239: FormatterWarning: Exception in text/plain formatter: Expand the range of the independent variable to allow two multiples of your tick locator (option `ticks`).
<snip>
KeyError: 'text/plain'

Current beta:

sage: sage: polar_plot(sec(x),(x,-pi/8,pi/8),ticks=[.1,None],aspect_ratio='auto')
/Users/.../sage/local/lib/python2.7/site-packages/sage/repl/rich_output/display_manager.py:570: RichReprWarning: Exception in _rich_repr_ while displaying object: unsupported operand type(s) for /: 'float' and 'str'
  RichReprWarning,
Graphics object consisting of 1 graphics primitive

But no graphic shows up. This warning is obviously much less helpful. It is true that the warning in both cases only appears once. Still this seems to be a fairly major regression.

CC: @vbraun

Component: graphics

Issue created by migration from https://trac.sagemath.org/ticket/19087

[vbraun]

comment:1

Its aspect_ratio='automatic'. Really the fault of plot for not verifying input and then tripping over its feet with useless diagnostics when its time to display the plot.

[kcrisman]

comment:2

I thought we had a 'auto'=='automatic' in that event? Man, I really have not been keeping up.

sage: polar_plot(sec(x),(x,-pi/8,pi/8),ticks=[.1,None],aspect_ratio='automatic') 
/Users/karl.crisman/Downloads/sage/local/lib/python2.7/site-packages/sage/repl/rich_output/display_manager.py:570: RichReprWarning: Exception in _rich_repr_ while displaying object: Expand the range of the independent variable to allow two multiples of your tick locator (option `ticks`).
  RichReprWarning,
Graphics object consisting of 1 graphics primitive

It still shouldn't say it returns a graphic object, should it?

[vbraun]

comment:3

plot() does return a graphics object, this is precisely what is wrong with plot. It shouldn't return a graphics object if the input is invalid. But it does, and the graphics object can't display itself graphically.

[kcrisman]

comment:5

Note that in the previous incarnation it didn't actually return anything, there was a KeyError...