tweaked the error message displayed when loading a project failed (issue #215) and replaced an error message by an assertion.
tweaked the error message displayed when loading a project failed (issue #215) and replaced an error message by an assertion.

aiivashchenko/appleseed,Biart95/appleseed,est77/appleseed,Biart95/appleseed,gospodnetic/appleseed,Biart95/appleseed,glebmish/appleseed,appleseedhq/appleseed,luisbarrancos/appleseed,appleseedhq/appleseed,Vertexwahn/appleseed,est77/appleseed,gospodnetic/appleseed,aytekaman/appleseed,aytekaman/appleseed,pjessesco/appleseed,Aakash1312/appleseed,Aakash1312/appleseed,luisbarrancos/appleseed,est77/appleseed,glebmish/appleseed,luisbarrancos/appleseed,Vertexwahn/appleseed,aytekaman/appleseed,docwhite/appleseed,pjessesco/appleseed,docwhite/appleseed,Vertexwahn/appleseed,gospodnetic/appleseed,gospodnetic/appleseed,dictoon/appleseed,aiivashchenko/appleseed,Aakash1312/appleseed,est77/appleseed,luisbarrancos/appleseed,dictoon/appleseed,Vertexwahn/appleseed,appleseedhq/appleseed,appleseedhq/appleseed,Biart95/appleseed,aytekaman/appleseed,est77/appleseed,glebmish/appleseed,glebmish/appleseed,luisbarrancos/appleseed,Aakash1312/appleseed,dictoon/appleseed,dictoon/appleseed,glebmish/appleseed,aiivashchenko/appleseed,aytekaman/appleseed,docwhite/appleseed,Vertexwahn/appleseed,docwhite/appleseed,dictoon/appleseed,pjessesco/appleseed,appleseedhq/appleseed,gospodnetic/appleseed,Biart95/appleseed,Aakash1312/appleseed,pjessesco/appleseed,docwhite/appleseed,aiivashchenko/appleseed,pjessesco/appleseed,aiivashchenko/appleseed