Creating a new page of template type Redirect and defining an external page (type the complete url, e.g. 'www.magnolia-cms.com') generate the following exception:

012-03-28 12:30:26,396 ERROR freemarker.runtime : Template processing error: "Expression model.externalLink is undefined on line 34, column 70 in templating-kit/pages/functional/redirectMain.ftl."

Expression model.externalLink is undefined on line 34, column 70 in templating-kit/pages/functional/redirectMain.ftl.
The problematic instruction:
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==> ${model.externalLink} [on line 34, column 68 in templating-kit/pages/functional/redirectMain.ftl]
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Java backtrace for programmers:
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freemarker.core.InvalidReferenceException: Expression model.externalLink is undefined on line 34, column 70 in templating-kit/pages/functional/redirectMain.ftl.
at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125)
at freemarker.core.Expression.getStringValue(Expression.java:118)
at freemarker.core.Expression.getStringValue(Expression.java:93)
at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.IfBlock.accept(IfBlock.java:82)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.IfBlock.accept(IfBlock.java:82)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.IfBlock.accept(IfBlock.java:82)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:221)
at freemarker.core.Environment.process(Environment.java:199)
at freemarker.template.Template.process(Template.java:237)
at info.magnolia.freemarker.FreemarkerHelper.render(FreemarkerHelper.java:155)
at info.magnolia.rendering.renderer.FreemarkerRenderer.onRender(FreemarkerRenderer.java:85)
at info.magnolia.rendering.renderer.AbstractRenderer.render(AbstractRenderer.java:136)
at info.magnolia.module.templatingkit.renderers.STKRenderer.render(STKRenderer.java:74)
at info.magnolia.rendering.engine.DefaultRenderingEngine.render(DefaultRenderingEngine.java:97)
at info.magnolia.rendering.engine.DefaultRenderingEngine$$EnhancerByCGLIB$$e113e8ec.render(<generated>)
at info.magnolia.rendering.engine.RenderingFilter.render(RenderingFilter.java:173)
at info.magnolia.rendering.engine.RenderingFilter.doFilter(RenderingFilter.java:113)
at info.magnolia.cms.filters.AbstractMgnlFilter.doFilter(AbstractMgnlFilter.java:91)