title: Plotting integral in sagemath gives `verbose 0 (3839: plot.py, generate_plot_points)`
body: <p>I plotted integral of function <code>x^2*sin(x^2)</code> in SageMath.</p>
  <p>It gives the following warnings and plot:</p>
  <pre class="lang-py prettyprint-override"><code>sage: plot(integrate(x^2*sin(x^2), x), (x, -6, 6))
  </code></pre>
  <pre class="lang-none prettyprint-override"><code>verbose 0 (3839: plot.py, generate_plot_points) WARNING:
    When plotting, failed to evaluate function at 35 points.
  verbose 0 (3839: plot.py, generate_plot_points) Last
    error message: 'unable to simplify to float approximation'
  Launched png viewer for Graphics object consisting of 129 graphics primitives
  </code></pre>
  <p><img src="https://i.stack.imgur.com/wkJws.png" alt="Plot of integral with SageMath" /></p>
  <p>How can i fix it?</p>