Do not crash when trying to compute equivalent widths when the nebular...

Do not crash when trying to compute equivalent widths when the nebular component emission is missing.

CHANGELOG.md

@@ -10,6 +10,7 @@
 ### Fixed
 - Corrected a typo that prevented `restframe\_parameters` from being listed among the available modules. (Médéric Boquien)
 - The filters in the residual plot of `pcigale-plots sed` are now drawn in order of increasing wavelength so that the line joining all the filters does not make loops. (Médéric Boquien)
+- In the absence of a nebular component `restframe\_parameters` would crash when attempting to compute the equivalent widths of the lines listed in `EW_lines`. Now they are simply ignored. (Médéric Boquien)
 
 ### Optimised
 - The cache architecture has been simplified, making it somewhat faster. It speeds up the model generation by ~1%. (Médéric Boquien)

pcigale/sed_modules/restframe_parameters.py

@@ -206,8 +206,9 @@ class RestframeParam(SedModule):
             sed.add_info("param.IRX", np.log10(sed.info['dust.luminosity'] /
                          (fluxes['FUV'] * self.to_lumin * c / 154e-9)))
 
-        for line, EW in self.EW(sed).items():
-            sed.add_info("param.EW({}/{})".format(*line), EW)
+        if 'nebular.lines_young' in sed.contribution_names:
+            for line, EW in self.EW(sed).items():
+                sed.add_info("param.EW({}/{})".format(*line), EW)
 
         for filt in self.lumin_filters:
             sed.add_info("param.restframe_Lnu({})".format(filt),