Unable to build search query: null

As seen on confluence.atlassian.com:

java.lang.NullPointerException
at com.atlassian.confluence.search.actions.SearchQueryBean.limitBySpaceVisibility(SearchQueryBean.java:276)
at com.atlassian.confluence.search.actions.SearchQueryBean.buildQuery(SearchQueryBean.java:103)
at com.atlassian.confluence.renderer.radeox.macros.SearchMacro.getHtml(SearchMacro.java:64)
at com.atlassian.renderer.macro.macros.AbstractHtmlGeneratingMacro.execute(AbstractHtmlGeneratingMacro.java:33)
at com.atlassian.confluence.renderer.radeox.filters.MacroFilter.handleMatch(MacroFilter.java:80)
at org.radeox.filter.regex.RegexTokenFilter$1.handleMatch(RegexTokenFilter.java:91)
at org.radeox.regex.JdkMatcher.substitute(JdkMatcher.java:48)
at org.radeox.filter.regex.RegexTokenFilter.filter(RegexTokenFilter.java:89)
at org.radeox.filter.FilterPipe.filter(FilterPipe.java:169)
at com.atlassian.confluence.renderer.radeox.AbstractRenderEngine.render(AbstractRenderEngine.java:69)
at sun.reflect.GeneratedMethodAccessor109.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.springframework.aop.framework.AopProxyUtils.invokeJoinpointUsingReflection(AopProxyUtils.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:149)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:116)
at com.atlassian.confluence.util.profiling.SpringProfilingInterceptor.invoke(SpringProfilingInterceptor.java:16)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:138)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:152)
at $Proxy23.render(Unknown Source)
at com.atlassian.confluence.renderer.radeox.RadeoxWikiStyleRenderer.convertWikiToXHtml(RadeoxWikiStyleRenderer.java:74)
at sun.reflect.GeneratedMethodAccessor122.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.springframework.aop.framework.AopProxyUtils.invokeJoinpointUsingReflection(AopProxyUtils.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:149)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:116)
at com.atlassian.confluence.util.profiling.SpringProfilingInterceptor.invoke(SpringProfilingInterceptor.java:16)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:138)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:152)
at $Proxy24.convertWikiToXHtml(Unknown Source)
at com.atlassian.confluence.spaces.actions.SpaceRssFeedAction.getPageXHtmlContent(SpaceRssFeedAction.java:47)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at ognl.OgnlRuntime.invokeMethod(OgnlRuntime.java:491)
at ognl.OgnlRuntime.getMethodValue(OgnlRuntime.java:904)
at ognl.ObjectPropertyAccessor.getPossibleProperty(ObjectPropertyAccessor.java:54)