Make final plot safer

bilby/core/sampler/dynesty.py

@@ -132,7 +132,8 @@ class Dynesty(NestedSampler):
     def __getstate__(self):
         """ For pickle: remove external_sampler, which can be an unpicklable "module" """
         state = self.__dict__.copy()
-        del state['external_sampler']
+        if "external_sampler" in state:
+            del state['external_sampler']
         return state
 
     @property
@@ -418,8 +419,8 @@ class Dynesty(NestedSampler):
         if self.check_point_plot:
             import dynesty.plotting as dyplot
             labels = [label.replace('_', ' ') for label in self.search_parameter_keys]
-            filename = "{}/{}_checkpoint_trace.png".format(self.outdir, self.label)
             try:
+                filename = "{}/{}_checkpoint_trace.png".format(self.outdir, self.label)
                 fig = dyplot.traceplot(self.sampler.results, labels=labels)[0]
                 fig.tight_layout()
                 fig.savefig(filename)
@@ -428,8 +429,8 @@ class Dynesty(NestedSampler):
                 logger.warning('Failed to create dynesty state plot at checkpoint')
             finally:
                 plt.close("all")
-            filename = "{}/{}_checkpoint_run.png".format(self.outdir, self.label)
             try:
+                filename = "{}/{}_checkpoint_run.png".format(self.outdir, self.label)
                 fig, axs = dyplot.runplot(self.sampler.results)
                 fig.tight_layout()
                 plt.savefig(filename)
@@ -438,15 +439,20 @@ class Dynesty(NestedSampler):
                 logger.warning('Failed to create dynesty run plot at checkpoint')
             finally:
                 plt.close('all')
-            filename = "{}/{}_checkpoint_stats.png".format(self.outdir, self.label)
-            fig, axs = plt.subplots(nrows=3, sharex=True)
-            for ax, name in zip(axs, ["boundidx", "nc", "scale"]):
-                ax.plot(getattr(self.sampler, f"saved_{name}"), color="C0")
-                ax.set_ylabel(name)
-            axs[-1].set_xlabel("iteration")
-            fig.tight_layout()
-            plt.savefig(filename)
-            plt.close('all')
+            try:
+                filename = "{}/{}_checkpoint_stats.png".format(self.outdir, self.label)
+                fig, axs = plt.subplots(nrows=3, sharex=True)
+                for ax, name in zip(axs, ["boundidx", "nc", "scale"]):
+                    ax.plot(getattr(self.sampler, f"saved_{name}"), color="C0")
+                    ax.set_ylabel(name)
+                axs[-1].set_xlabel("iteration")
+                fig.tight_layout()
+                plt.savefig(filename)
+            except (RuntimeError, ValueError) as e:
+                logger.warning(e)
+                logger.warning('Failed to create dynesty stats plot at checkpoint')
+            finally:
+                plt.close('all')
 
     def generate_trace_plots(self, dynesty_results):
         check_directory_exists_and_if_not_mkdir(self.outdir)